Villar A S, Cruz L S, Cassemiro K N, Martinelli M, Nussenzveig P
Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, 05315-970 São Paulo, São Paulo, Brazil.
Phys Rev Lett. 2005 Dec 9;95(24):243603. doi: 10.1103/PhysRevLett.95.243603.
We present the first measurement of squeezed-state entanglement between the twin beams produced in an optical parametric oscillator operating above threshold. In addition to the usual squeezing in the intensity difference between the twin beams, we have measured squeezing in the sum of phase quadratures. Our scheme enables us to measure such phase anticorrelations between fields of different frequencies. In the present measurements, wavelengths differ by approximately 1 nm. Entanglement is demonstrated according to the Duan et al. criterion [Phys. Rev. Lett. 84, 2722 (2000)] Delta2p- + Delta2q+ = 1.41(2) < 2. This experiment opens the way for new potential applications such as the transfer of quantum information between different parts of the electromagnetic spectrum.
我们展示了对阈值以上工作的光学参量振荡器产生的孪生光束之间压缩态纠缠的首次测量。除了孪生光束强度差的通常压缩外，我们还测量了相位正交和的压缩。我们的方案使我们能够测量不同频率场之间的这种相位反关联。在当前测量中，波长相差约1 nm。根据段路明等人的标准[《物理评论快报》84, 2722 (2000)]，证明了纠缠：Δ2p− + Δ2q+ = 1.41(2) < 2。该实验为诸如在电磁频谱不同部分之间转移量子信息等新的潜在应用开辟了道路。
